Review of Existing Coastal Reservoirs and its Global Application

In the world there exist two types of reservoirs, whose dams are situated in freshwater and seawater environment, respectively, i.e., inland dams and coastal reservoirs. This paper reviewed dam development and particular attention was paid to coastal reservoirs. It is found that for water supply, the inland dams are gradually petered out, but the numbers of coastal reservoirs are increased steadily. The analysis shows that most of the inland dams may be outdated in year 2150. In this paper, 67 coastal reservoirs were listed and reviewed from developed counties like Australia, the Netherlands, UK, Singapore, Japan and South Korea to developing countries like China and India. The earliest coastal reservoir still in operation today was constructed in China about 1185 years ago, the earliest modern coastal reservoirs were constructed in 1930s, namely the Zuiderzee in the Netherland and Alexandrina-lake in Australia. This review reveals that similar to inland dams which are constructed for different purposes, coastal reservoirs are constructed for prevention of seawater intrusion, land reclamation, flood control and water supply. After 1960s, majority of coastal reservoirs were constructed for water supply. Hong Kong is the first city whose water supply comes from the coastal reservoir, and Shanghai is the largest city whose water scarcity is solved by coastal reservoirs. Almost all existing coastal reservoirs are the 1^st generation, which fully closes a river mouth and causes problems in water quality and ecosystem. The 2^nd generation coastal reservoir is proposed without closing a river mouth fully and permanently. The preliminary analysis shows that coastal reservoirs may be useful for world coastal cities if there exists sufficient runoff, its application to the driest and the second driest continents as well as the Middle East is also discussed.